Arrival date, age and breeding success in white stork Ciconia ciconia

摘要

Early arrival to breeding grounds is a life history trait in birds that can result in fitness benefits. We studied therelationship between arrival date and breeding success of individuals in a central Iberian population of whitestork Ciconia ciconia, between 1999 and 2005, and the ways in which other potential factors, such as age or sex,affect this relationship. Our results showed that age was the factor most closely related to arrival date andbreeding success. Older individuals returned earlier to the breeding grounds, achieved larger clutch sizes andproduced more chicks than younger birds. After controlling statistically for age effect, breeding probability (laideggs or not) and laying date were still significantly explained by arrival date. A higher probability of failure toreproduce (no eggs laid) was found in birds arriving later than in those arriving early. However, clutch size andnestling success (number of nestlings in the nest 40 days after hatching) were not correlated with arrival date.Food availability in the study area throughout the breeding cycle, due to a nearby rubbish dump, could be thefactor mitigating differences in clutch size and nestling success related to individual arrival date.